1. Field of the Invention
The invention relates to a method and apparatus for form-processing paper in a printing press by means of at least one processing tool. What is meant herein by form-processing is the forming of scores, creases, perforations or the like in the paper.
It has become known heretofore for such forming tools as cutting or scoring tools or perforating tools to be integrated into a printing press, so that the paper, after being printed, need not be separately cut to size or prepared for folding., The textbook entitled Maschinenbau [Machine Construction], VEB Verlag Technik Berlin 1968, Vol. 3/II, Chapter 1.5.3.5, pages 597-598, for example, shows a combined printing press and punching machine.
If a new printing job is to be performed with such a machine, generally the processing tools must be changed, or at least adjusted.
2. Summary of the Invention
It is accordingly an object of the invention to permit rapid and economical variation of processing geometries when form-processing paper in a printing press.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for form-processing paper in a printing press by means of at least one processing tool and a computer, which comprises converting digital data representing desired processing geometries into signals in the computer, and controlling the at least one processing tool with the signals so as to obtain the processing geometries.
In accordance with another mode of the method according to the invention, the form-processing includes at least one of the processes of cutting, perforating, scoring and stitching.
In accordance with a further mode, the method according to the invention includes separately generating with the printing press the digital data for representing the processing geometries, and then transmitting the data to the printing press computer for calculating the control signals for the at least one processing tool.
In accordance with an added mode of the method according to the invention, the generation of the digital data is performed within the context of the printed product design in an electronic printing precursor stage, and the method includes adding color information to the digital data in a manner that one color, respectively, is assigned to each type of processing.
In accordance with an additional mode of the method according to the invention, the generation of the digital data in the printing precursor stage is in the form of postscript data, and the method includes converting the postscript data into a pixel pattern including at least one pixel pattern for one color to be printed and at least one pixel pattern which has a color assigned to one type of processing, and calculating in the printing press computer the control signals for the corresponding processing tool from the at least one pixel pattern.
In accordance with yet another mode, the method according to the invention includes defining a plurality of zones along the width of the printing press, assigning at least one processing tool to each of the zones and, during operation of the printing press, positioning and activating and deactivating the processing tools in a manner required by processing geometries in the corresponding zone.
In accordance with yet a further mode of the method according to the invention, the form-processing is performed with at least one beam of light, and the method comprises either tracking the contours to be form-processed or linearly scanning the surface of the paper, including turning the light beam on only at the contours to be form-processed.
In accordance with yet an added mode, the method according to the invention includes imprinting the geometry to be form-processed prior to processing with a color which absorbs the light used for the processing.
In accordance with yet an additional mode, the method according to the invention includes generating the light by laser.
In accordance with another aspect of the invention, there is provided an apparatus for form-processing paper in a printing press having at least one paper form-processing tool disposed adjacent to a paper path, comprising a computer having an input for digital data representing desired processing geometries and an output for control signals, the at least one processing tool being operatively connected to the computer and being activatable and deactivatable by the control signals, the at least one processing tool being positionable at least in part along the width of the printing press.
In accordance with another feature of the invention, the at least one paper form-processing tool is selected from the group consisting of a mechanical cutting tool, a perforating tool, a scoring tool and a stitching tool, and a water-jet cutting device.
In accordance with a further feature of the invention, the at least one paper form-processing tool is selected from the group consisting of a focused beam of light, a laser, and a laser optical element.
In accordance with an added feature of the invention, the apparatus includes a plurality of zones defined along the width of the printing press, and a plurality of the paper form-processing tools disposed along the width of the printing press and, respectively, assigned to each of the zones.
In accordance with an additional feature of the invention, the plurality of paper form-processing tools form a paper form-processing unit mountable on the printing press.
In accordance with yet another feature of the invention, the paper form-processing unit has a laser diode array extending over the width of the printing press.
In accordance with yet a further feature of the invention, the laser diode array is stationary, and at least one optical element is disposed between the laser diode array and a surface of paper.
In accordance with yet an added feature of the invention, the at least one optical element focuses light from at least one diode of the diodes of the laser diode array onto at least one focal point located on the paper.
In accordance with a concomitant feature of the invention, the at least one optical element is movable crosswise to the paper path.
By the foregoing provisions, the pressman is relieved of the task of arranging the processing tools to fit the printing job. The corresponding make-ready or conversion times are eliminated. The digital data for defining the geometry can be generated by means of available software and hardware which is used for designing the printed product in the electronic printing precursor stage. In other words, type-setting and the defining of the geometry can be performed in a single operation, and the processing task can subsequently be performed largely automatically.
In an apparatus for form-processing paper in a printing press having at least form-processing tool disposed adjacent to the paper path, the foregoing object is attained in accordance with the invention in that the at least one processing tool is activatable and deactivatable by means of the control signals and can at least in part be positioned along the width of the printing press, and a computer is provided which has an input for digital data representing desired processing geometries and an output for the control signals.
For greater freedom in construction or design and for higher processing speed, preferably a plurality of optionally different types of form-processing tools are used over the entire width of the paper, each of the tools being positionable and activatable and deactivatable, respectively, within an assigned zone along the width of the machine by means of the control signals.
Particularly great construction or design freedom is obtained if the processing is performed by focused light, for example, of the type produced by lasers; in that case, rounded corners and other filigreed contours can be produced quite easily. Compared with a combined printing press and punching machine with a male and female punching die, the copies printed on one sheet of paper to be printed can be spaced closer together, and the yield of imprinted material is greater, because no forces or only very slight forces, respectively, of separation and expulsion act perpendicularly to the surface of the imprinted material, and thus the stabilizing function of the skeleton formed by the trimmings is dispensed with.
It is true that cutting paper by laser has become conventional; see for example the article, xe2x80x9cPapierschneiden mit Laserxe2x80x9d [Paper Cutting by Laser] by H. Federle and S. Keller in the journal, Papier und Kunststoff-Verarbeiter [Paper and Plastics Processor], Number 9/92, pages 54-59. The versatility of laser cutting devices is of particular significance, however, if it is used in combination with printing presses as in the invention. Because digital data which represent the processing geometries can be produced in combination with the typesetting, and it is no longer necessary to make adjustments to the printing press itself, the invention makes it possible to form-process paper in a printing press with immediately variable processing geometries. Small runs of printed products which require complicated form-processing thus become considerably more economical. This is true to an even greater extent for digital printing presses which can be used as page printers because, with the invention, it is even possible for each page to undergo an individualized form-processing without impairment of the printing speed.
In digital printing presses, the method and apparatus according to the invention can moreover be achieved especially simply. For example, if the printing press computer already includes an RIP (raster image processor), which breaks down the digital data, generated as postscript data and representing the pixels and the colors thereof, into pixel patterns for the colored partial images then, in the printing precursor stage, the processing geometries and the kinds of form-processing are shown in the same format as the pixels and image colors. The software normally used in typesetting offers suitable capabilities for accomplishing this; one example is identifying one processing geometry and one type of form-processing by means of a frame having a color which is defined as a special color designated as xe2x80x9ccuttingxe2x80x9d. Because the processing geometries and types of form-processing are handled like special colors, the RIP generates a special pixel pattern for each kind of form-processing; this pattern is then suitably interpreted by the printing press computer and converted into the control signals for the form-processing tools.
Accordingly, to use the invention in a digital printing press, all that is needed is to provide a unit for actually performing the form-processing task. Otherwise, the existing devices and control methods can be used. Even older printing presses, however, can be retrofitted with such a unit without difficulty. The pixel patterns for the processing geometries are produced in this case in the RIP of a typesetting computer, for example. Moreover, lasers are not the only suitable form-processing tools. Given a suitable arrangement and combination, thoroughly flexible form-processing can be accomplished with mechanical processing tools.
On the other hand, in the case of contactless processing, for example using a laser, a further mode of the method according to the invention may be considered, which is for the geometry which is to cut, for example, to be preprinted using a light-absorbent printing ink, before performing the form-processing. The color may be black, for example, or may be visually imperceptible, as long as its light absorption is tuned to the spectrum of the cutting light and at least partially coincides therewith. Preprinting the cutting geometry has the following advantages: a defined absorption of the laser light is attained, which minimizes the influence upon the cutting capacity of the material to be imprinted, and thus minimizes the necessary adjustments and adaptations of the light parameters to the substrate; the cutting capacity is better because of the higher energy yield; a perforation need not be generated by modulating the beam of light; instead, it can be produced by means of a suitably preprinted broken line and a constant light incidence, thereby reducing the computer capacity and control expenditure required; the beam of light need not be focused precisely at the surface of the paper, so there is less vulnerability in terms of spacing distance and thus less tolerance to fluttering of the paper, for example; and the tracking of the beam need not be so exact.
Because less stringent demands are made with respect to focusing and because of the defined light absorption, it is, moreover, not absolutely necessary to use lasers for form-processing preprinted processing geometries; instead, conventional light sources can also be considered.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in apparatus for form-processing paper in a printing press, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.